Additional malignancies and mortality in uveal melanoma: A 20-year follow-up of a Norwegian patient cohort

Purpose: The purpose of this study is to explore the frequency of additional primary malignancies in uveal melanoma (UM) patients and cause-specific mortality, to help guide surveillance strategies after UM.

Methods: All patients diagnosed with UM at Oslo University Hospital during 1990-2017 were eligible for inclusion. Linkage to the Cancer Registry of Norway obtained information on additional malignancies and cause of death throughout 2019. UM patients were categorized according to timing of additional malignancy (prior/simultaneously or after UM) or no additional cancer, and by UM stage at diagnosis. Age-adjusted mortality rates were presented per 1000 person-years with 95% confidence intervals (CI).

Results: The study population included 960 UM patients: 77% were diagnosed in stage and I/II and 56% were men. Mean age at diagnosis was 63 years. Additional malignancies were observed in 152 patients prior/simultaneous to UM, and in 120 patients >1 year after UM. Overall, mortality per 1000 person-years was 3.5 (95% CI 3.1-3.9) for UM and 3.0 (2.6-3.4) for other causes. Lowest UM mortality [1.3 (0.60-2.1)] was seen in patients with a second malignancy after UM, regardless of stage. Highest UM mortality was seen for UM patients in stage III/IV, both without [16.1 (13.2-19.1)] and with any additional malignancy [16.9 (6.6-27.3)].

Conclusion: Our results support that UM patients frequently have additional malignancies, both before and after UM. Low-UM mortality in patients with a primary malignancy after UM, might indicate less aggressive UM. The cumulative UM mortality flattens about 10 years after diagnosis and annual follow-up of patients for 10 years seems adequate.